A comparison of K^trans measurements obtained with conventional and first pass pharmacokinetic models in human gliomas

Abstract

Purpose:To compare in a group of patients with cerebral gliomas the estimates of K trans between a conventionally established pharmacokinetic model and a recently developed first pass method. Materials and Methods:Glioma patients (23) were studied using T 1 -weighted dynamic contrast-enhanced magnetic resonance imaging (MRI), and two alternative pharmacokinetic models were used for analysis to derive the volume transfer constant K trans . These were a modified version of the established model (yielding K TK ) and a recently published method based on first pass leakage profile (FP) of contrast bolus (yielding K fp ). Results:We found a strong correlation between intra-tumoral median K TK and K fp (rho ϭ 0.650, P Ͻ 0.01), but the values from the conventional model were consistently and significantly higher (mean of inter-tumoral K fp and K TK medians were 0.018 minute -1 and 0.284 minute -1 , respectively, P Ͻ 0.001). The spatial distribution of K TK and K fp showed poor correlation in the presence of large vascular structures and good correlation elsewhere.Conclusion: K TK and K fp produce similar biologic information within voxels not dominated by vascular tissue. The FP method avoids erroneous overestimation of K trans in areas of significant intravascular contrast. Findings are in keeping with the predictions of previous mathematical simulations.

Glioma: Application of Histogram Analysis of Pharmacokinetic Parameters from T1-Weighted Dynamic Contrast-Enhanced MR Imaging to Tumor Grading

“…20,30,31 The estimation of the baseline T1 is very sensitive to noise that is present in multiple flip angle and DCE images, and this sensitivity results in the broadening of the baseline T1. The fixed baseline T1 can contribute to obtaining more consistent results and can protect dynamic data from incorrect scale factors or patient movements during DCE data collection.…”

“…Ve is the extravascular extracellular space per unit volume of tissue and is known as leakage space. 19,20 Vp is defined as the blood plasma volume per unit volume of tissue, which may be a marker of angiogenic activity in a tumor. 13 However, previous studies collected the perfusion data from parts of entire-tumor volumes.…”

Quantification of cerebral blood flow, cerebral blood volume, and blood–brain‐barrier leakage with DCE‐MRI

“…The feasibility of measuring CBF, which requires a higher temporal resolution, has been demonstrated more recently (28,29). In tumors, where blood volumes are typically higher, CBV measurement is inherently less problematic (26), has equal diagnostic quality as DSC-MRI (30), and can be performed simultaneously with a measurement of permeability (31)(32)(33).…”

Methodological developments and clinical applications of pharmacokinetic models in contrast-enhanced magnetic resonance perfusion studies

“…The application of these models is complex and has important variability sources, both in image acquisition and in post-processing methodologies. Although there is a huge amount of studies and applications [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], the methodological complexity and the dependency on the model variant do not allow the reproducibility of the results among clinical centers [5,11,22]. However, it has been accepted that the PK analysis should be theoretically independent from both the patient and the equipment, because it works directly on contrast concentration values, instead of only signal intensity variations.…”

“…Although it is not a standardized protocol, most centers roughly coincide in the main points [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”